This invention relates to a distance meter which is used in cameras or the like apparatus to measure a distance to an object. This invention also relates to a camera or the like apparatus having such distance meter.
In the distance metering, there have been known distance meters which measure a distance to an object by the so-called "passive method". Such a known distance meter is described with reference to FIG. 14. This distance meter is provided with an optical system and a line sensor arranged behind it, and rays of light coming from an object pass through lenses 51L, 51R. The rays having passed through the lenses 51L, 51R are reflected by mirrors 52L, 52R at right angles with respect to optical axes to be directed to line sensors 54L, 54R in which light receiving elements corresponding to a specified number of pixels are arrayed. The rays reflected by reflecting surfaces 53L, 53R of a prism 53 are focused as an object image on the sensing surfaces of the line sensors 54L, 54R by the focusing action of the lenses 51L, 51R. The object images focused on the sensing surfaces of the line sensors 54L, 54R are photoelectrically converted by the line sensors 54L, 54R into left and right image signals, respectively.
The left and right image signals obtained by the line sensors 54L, 54R are converted into left and right data series by an analog-to-digital (A/D) converter or the like, respectively. Some of the left and right data are extracted by a data extractor 55. A correlation calculator 56 correlates extracted pixel data to one another to obtain a sequence of correlation values. Thereafter, a distance calculator 57 calculates distance data corresponding to the position where the correlation value is at minimum within the obtained sequence, and a drive signal generator 58 generates a drive signal based on the obtained distance data.
However, data for correlation is extracted in a single fixed shifting manner. Consequently, there has been the likelihood that satisfactory accuracy cannot be attained when metering a distance to a particular object. Specifically, a wrong correlation value is likely to be judged as a minimum correlation value in the case of metering a distance to an object having a repetition pattern image or a distance to an object locating in an end of line sensors.